DMDX Alternatives

DMDX

DMDX is a Win 32-based display system used in psychological laboratories around the world to measure reaction times to visual and auditory stimuli. It was programmed by Jonathan Forster at the University of Arizona.

DMDX uses DirectX. This software gives the Windows programmer better access to the actual hardware, which is essential for accurate timing. It is generally believed that it is virtually impossible in a Windows program to get accurate timing of displays, or accurate measurement of reaction times. This is true for applications that do not make use of DirectX, but not for DMDX.

DMDX comes with a sister program called TimeDX. This program is designed to establish the properties of your machine (graphics resolution, refresh rates, type of sound card, presence of PIO card, etc.), and to record these in the Windows Registry, so that DMDX will know what kind of machine it is running on. Both TimeDX and DMDX have their own Help files.

What hardware do you need?

* Pentium PC (or better, including Celeron, AMD K6). These CPUs come with a motherboard that has a High Performance Timer which is essential for DMDX.

* Plenty of RAM -- 32M at least.

* For dual screen displays, either (a) a video splitter to duplicate the output on two monitors (one for the experimenter, one for the subject), or (b) you can take advantage of the MultiMonitor option in Windows 98/ME (not 95), which permits the programmer to write to multiple screens (DMDX just uses two). In this case you need two graphics cards, rather than a video splitter.

* A fast video card with 4M of on-board memory.

* Sound card (not essential if you are not using audio)

* Input device for the subject's response: PIO12 i/o card, keyboard, mouse, game pad, joystick (just the buttons). These vary in their accuracy of measurement of RTs.